Control mountings for helicopter rotors



Nov. 25, 1958 I. B. BENSEN 2,8

CONTROL MOUNTINGS FOR HELICOPTER ROTORS,

Filed Feb. 28, 1955 v 4 Sheets-Sheet l INVENTOR I I I602 5i 550 55 BYATTORNEY Nov. 25, 1958 1. BENSEN CONTROL MOUNTINGS FOR HELICOPTER ROTORSFiled Feb. 28, 1955 4 Sheets-Sheet 2 INVENT OR 160/? 5. fils/vsf/vATTORNEY WME I. B. BENSEN CONTROL MOUNTINGS FOR HELICOPTER ROTORS FiledFeb. 28, 1955 Nov. 25, 1958 4 Sheets-Sheet 3 INVENTOR 160/2 5. 55/1/55ATTORNEY Nov. 25, 1958 .1. B.-B EN$EN CONTROL MOUNTING$ FOR HELICOPTERROTORS Filed Feb. 28, 1955 4 Sheets-Sheet 4 ATTORNEY CONTROL MOUNTINGSFOR HELICOPTER ROTORS Igor B. Benson, Raleigh, N. C.

Application February 28, 1955, Serial No. 490,883

2 Claims. (Cl. 170-16027) This invention relates to helicopters and,more parglciularly, to combined rotor mount and control assem- Theobject of the invention is to provide an extremely simple, light anddurable assembly for mounting a rotor on the top of a fuselage, wherebythe axis of rotation of the rotor may be universally tilted, and wherebythe pilot maintains direct and instinctively natural control over thetilting adjustments of the rotor. p

More particularly, it is intended now to provide a generally verticalrotor shaftpivotally mounted on the fuselage above the pilot seat of ahelicopter, the rotor turning on-the shaft above the fuselage, and acontrol stick extending downwardly from the rotor shaft so that-when thecontrol stick is swung forwardly and rearwardly, or from side to side,therotor shaft is correspondingly tilted about its'pivotal mounting, andthe rotor follows the tilting of the rotor shaft. The instinctivelynatural reaction obtained by the control system-of this invention has todo with the native balancing reactions of a pilot, i. e., when hedesires to travel to the right, for example, the natural motion of acontrol stick suspended froma point above the pilot is to the left.Similar reactions prevail for the up-and-down tiltings of the helicopterobtained in this instance by back and forward motions of-the controlstick.

The illustrated embodiments of the invention are in association with agyro glider, although it will be apparent that the invention may beadapted to powered helicopters, wherein the saving of weight, simplicityof construction, and ease of operation are of the essence. In contrastwith the usual control systems utilizing blades individually pivoted ona'hub for adjustment about their feathering axes to vary the total andcyclic pitch, and comparatively elaborate linkage for controlling theblades, this invention provides a tiltable rotor shaft, and a rotor hubpivotally mounted on the rotor shaft so that the axis of rotation of theteetering rotor will follow the tilting motions of the rotor shaft. 7

In one embodiment of the invention, it is intended that the rotor shaftshall turn with the rotor, the rotor hub being rockably mounted on therotor shaft, and the rotor shaft being rotatably mounted in a sphericalbearing in the top of the fuselage so that the rotor shaft may beuniversally tilted from its normally vertical position.

In second, thirdan'd'fo-urth forms of the invention, the rotor hub ismounted through a teeter hinge over a straight thrust bearing on anon-rotating rotor shaft so that the rotor will bo th turn and teeter onthe non-V rotating shaft. Provision is made for tilting the rotor shaftwith respect to the fuselage on which it is mounted,

one form including a resilient bearing in the fuselage, another formconsisting of gimbals, and still another form comprising a universaljoint.

These and other objects will be apparent from the followingspecificationsanddrawings, in which:

Fig. 1 is a side elevation of a gyro glider embodying one form of theinvention;

Fig. 2 is an enlarged view of the upper portion of the fuselageillustrating in vertical cross-section, the details of the Fig. lembodiment;

Fig. 3 is a view similar to Fig. 2 but illustrating a second form of theinvention;

Fig. 4 is a view similar to Figs. 2 and 3 but illustrating a third formof the invention; and,

Fig. 5 is a fragmentary view similar to Figs. 2, 3 and 4, butillustrating a fourth form of the invention.

Referring now to the drawings in which like reference numerals denotesimilar elements, the gyro-glider illustrated in Fig. 1 comprises afuselage 2 of open-box-like configuration having a landing gear 4, and acable hitch 6'by which it is towed. Pins 7 stabilize flight andcounteract tendencies toward'side thrusts resulting from resilientfunction in the hub. The pilot sits in a seat 8, and lift results fromrotation of'a rotor R comprising rotor blades 10 fastened by plates 12at their inner ends to a rotor hub 14 by bolts 15. Pillow blocks 16fastened as indicated at 17 at the center of hub 14 are connected by ateeter pin 18 to the upper end of a rotor shaft 20 which is supportedgenerally vertically between the converging ends of the members 22, 22aat the upper end of the fuselage. It will be understood that while inthe present embodiment there are three such members converging inwardlyand upwardly. from the respective corners of the fuselage, that variousother fuselage structures and configurations may be used. This inventionis concerned primarily with the mounting of rotor shaft 20 in fuselage2, the mounting of rotor hub 1-4 on the rotor shaft, and theirrelationship to the control stick 30 detailed hereinafter.

Referring now to Fig. 2, there is shown an annular plate-shaped rotorhead bearing block 24 secured, as at 25, to the inner ends of fuselagemembers 22, the rotor head bearing block supportingin its innerperiphery an outer race of a spherical bearing 26. An inner hearing race27 affixed around rotor shaft 20rollingly supports a plurality ofbarrel-shaped rollers 28 so that, thus rotatably mounted, rotor shaft 20is free to tilt, within certain prescribed limits, from the vertical. Itwill be understood that conventional bearing retainers and installationstructures are used with the bearing parts.

Control stick 30, whichextends downwardly in front of the pilot station,is fixed, as at 32, to a control stick bearing housing 34 having, nearits center, a pair of outer ball races 36, 38 lying opposite inner ballraces 40, 4?. on shaft 20. Bearing balls 43 rolling between the innerand outer races provide for free rotation of shaft 20 within the controlstick bearing housing. A nut 44 and Washer 45 hold the assembly on thelower end of shaft 20, and a spacer 46 separates the bearingassembliesfrom one another. Thus, when control stick 30 is swung in onedirection or another, rotor shaft 20 is correspondingly tilted from itsnormal generally vertical position.

An anti-rotation and travel-limit coupling is provided between the rotorhead bearing block 24 and control stick bearing block 34, this beinga-guide strip 47 se cured as at 48 to control stick bearing block 34 andprovided, near its other end, with a slot 50 through which projects apin bolt 52 rigidly projecting from rotor head bearing block 24. By thismeans, control stick 30 is prevented from turning with rotor shaft 20,and limits the motion of the rotor shaft 20 in its spherical bearing 26by abutting engagement of pin bolt 52 with the ends of slot 50. Theteeter motion of rotor R is limited by stops 54 secured as at 56 to thehub bolts 17 so that teeteringof the rotor assembly beyond desiredlimits 9 a is prevented by engagement of stops .54 with the top of rotorhead assembly block 24.

When control stick 30 is, for instance, pulled back, rotor shaft 20tilts in spherical bearing 26 so that its upper end tilts forwardly. Asthe rotor R teeters about teeter pin 18, its axis of rotation soonfollows and coincides with the axis of rotor shaft 20 so that a forwarddrive and upward lift of the craft is imparted by rotor R.

Tilting of the control stick to the right or left results indifferential pitch control of the opposite blades 12, 12 in that theangle of attack of the blade momentarily disposed towards the front ofthe craft is increased, whereas the attack angle of the blademomentarily at the rear is correspondingly decreased.

In the embodiments illustrated in Figs. 3, 4 and 5, the structure andmounting of rotor R on teeter pin 18 is the same as in Figs. 1 and 2.However, rotor shaft a is affixed, as at 58 on a straight thrust bearing59 having a housing 60, containing a cylinder 61 having outer bearingraces 62, 64 therein. A sleeve 66 is formed with inner bearing races 68,70 sothat bearing ball sets 70, 72 rotatably support rotor shaft 20a. 7

Referring now to Fig. 3, sleeve 66 of the thrust bearing assembly isaffixed around a post 76a. Around post 76a are afiixed a spacer 78 andthe inner metal annulus 80 of a resilient mount 82 which supports therotor assembly on fuselage 2. An annular disc 84 of resilient material,such as rubber, fits tightly around inner annulus 80 and is confinedwithin an outer metal annulus secured at 88 to the inner ends offuselage members 22, 22a. Below inner annulus 80, control stick 30a iswelded at 90 to a mounting sleeve 92 held on post 76a by a nut 94threaded on the lower end of the post. Teeter motion stops 54a securedat 56 by bolt 17 engage the top of outer annulus 86 so as to limit theteeter motion.

In operating the Fig. 3 embodiment, rotor R teeters about pin 18, andshaft 20a is rotatably mounted by thrust bearing 59 on post 76a, theentire assembly being universally tiltable by manipulating control stick30a. The resilient disc 84 provides elastic centering forces tending toreturn post 76a to its normally vertical position. Disc 84 also absorbsvertical vibration and prevents rotation of control stick 30a about therotor axis.

The embodiment illustrated in Fig. 4 is comparable to that of Fig. 3except in that post 76b is supported for universal tilting movement bygimbals 96, which include a pivot pin 93 extending across an inner ringand through post 76b, and transverse pivot pins 102 pivotally supportinginner ring 100 in an outer ring 104, the outer ring being fastened at104 to fuselage members 22, 22a. Control stick 30a is secured at 90 to asleeve 92 held on the reduced lower end 93 of post 76b by nut 94threaded around the lower end of the post.

As in the previous embodiments, teeter motion stops v 54b are secured at56 by bolt 17 to hub 14 so that, upon predetermined teetering of rotorR, outer gimbals ring 104 is engaged by stop 54b to prevent excessiveteetering motion.

In the Fig. 5 embodiment, the supporting post for thrust bearing 59 isformed with upper and lower portions 76c, 760 connected by a universaljoint 106 so that rotor R may be universally tilted. Aflixed aroundupper portion 76c above the universal joint is a sleeve '92" to whichcontrol stick 30a is welded, as at 92. The reduced lower end 108 oflower post portion- 760" is supported in an apertured base plate 106 inwhich the inner ends of fuselage frame members 22", 22a" are afiixed at112. Tilt limit stops, not shown, are mounted on base plate 110 toengageupper post portion 76c on four sides thereof upon predetermined tiltingof the assembly above the universal joint 1106, thereby stopping upperpost portion 76c and the elements supported thereon from flopping overwhen rotor R isinactive, but permitting sufficient universal tilting ofupper post portion 760 to effect the desired controls. A teeter stop 540secured at 56 by bolt 17 to hub 14 engages an abutment collar 114 weldedat 116 around bearing housing 60 to prevent excessive teetering of rotorR.

The invention has been found to be particularly useful in a gyro-gliderof such elementary form that it can be assembled by beginners who,self-taught, learn to fly it by being towed behind an automobile or bypracticing in the prop-wash of an airplane, or simply kiting in a strongwind.

The invention is equally applicable to powered helicopters and all othertypes of rotary ring aircraft.

The invention described above is not limited to the illustrated details,but is intended to cover all substitutions, modifications andequivalents within the scope of the following claims.

I claim:

1. In a rotating wing aircraft, a fuselage, a rotor com prising a huband blades afiixed to and radiating therefrom, a normally generallyvertical rotor shaft, bearing means rotably supporting said hub on'saidshaft whereby the rotative plane of said blade may tilt with respect tothe axis of said shaft, universal pivot means supporting said shaft insaid fuselage whereby said shaft may be tilted with respect to saidfuselage, said universal pivot means comprising a resiliently deformablesupporting member connected at spaced portions thereof to said shaft andfuselage, respectively, said member providing elastic centering forcestending to maintain said shaft vertical and providing a resilientsupport for said shaft in said fuselage, and control means for tiltingsaid shaft, said member comprising a generally flat annular disc havinginner and outer peripheries, the connection at spaced portions thereofto said shaft and fuselage comprising means affixing the inner peripheryof the disc around the shaft and means affixing the fuselage to theouter periphery of the disc, substantially the entire weight of theaircraft being supported by said disc.

2. In a rotating wing aircraft, a fuselage including a plurality offrame members converging at the upper end of the frame, a ring rigidlyaffixed to the converging ends of said frame members, a substantiallyflat annular disc of resiliently deformable material having an outerperiphery compressed within said ring, said disc being disposedsubstantially horizontally and the diametrical extent of the materialforming the upper and lower sides thereof being substantially greaterthan the axial thickness thereof, a normally vertical shaft extendingaxially within the inner periphery of the disc, means substantiallyrigidly afiixing the inner periphery of the disc around said shaft, abearing rotatably mounted on said shaft above said disc, a rotorcomprising a hub and blades radiating therefrom, a teeter connectionbetween said hub and said bearing, and a control stick rigidly affixedon said shaft below said disc, the resilient deformability of said ringproviding for universal tilting movements of said shaft by said controlstick and also providing elastic centering forces tending to maintainsaid shaft in vertical disposition.

References Cited in the file of this patent UNITED STATES PATENTS2,224,357 Pecker Dec. 10, 1940 2,264,942 Larsen Dec. 2, 1941 2,429,502Young Oct. 21, 1947 2,510,006 Young May 30, 1950 2,631,679 Hiller Mar.17, 1953 2,658,575 Stone Nov. 10, 1953 2,677,431 Prince May 4, 19542,689,011 Zakhartchenko Sept. 14, 1954 2,702,601 Nagler Feb. 22, 1955FOREIGN PATENTS 459,070 Canada Aug. 23, 1949

